The present invention relates to new zinc/metal hexacyano-cobaltate complex compounds which can be used as catalysts, to a process for their production, and to the production of polyether polyols from these novel zinc/metal hexacyano-cobaltate complex compounds.
Double metal cyanide (DMC) complex compounds are known to be suitable catalysts for the polyaddition of alkylene oxides to starter compounds containing active hydrogen atoms. Such catalysts and processes for producing polyether polyols from these catalysts are as described in, for example, U.S. Pat. Nos. 3,404,109, 3,829,505, 3,941,849 and 5,158,922. In particular, the use of these double metal cyanide complex compounds as catalysts for the production of polyether polyols leads to a reduction of the proportion of monofunctional polyethers containing terminal double bonds, so-called monools, in comparison to the conventional production of polyether polyols using alkali metal catalysts, such as alkali metal hydroxides.
U.S. Pat. No. 5,470,813 and JP Patent 4,145,123 disclose improved double metal cyanide complex compounds that enable the proportion of mono-functional polyethers containing terminal double bonds to be reduced still further in the production of polyether polyols. Furthermore, the use of the improved double metal cyanide complex compounds reduces the induction time in the polyaddition reaction of the alkylene oxides to corresponding starter compounds and also increases the catalyst activity.
The object of the present invention is to provide further improved double metal cyanide (DMC) complex compounds which are suitable for use as catalysts in a process for the polyaddition of alkylene oxides to corresponding starter compounds, wherein these catalysts have a considerably reduced induction period compared to the previously known types of catalysts. A reduction of the induction period results in an improved economy of the process by decreasing the cycle time of the polyether polyol production. A further aim of the present invention is to achieve as narrow a molecular weight distribution as possible in the polyether polyols which are produced. The narrowest possible molecular weight distribution in the polyols is of great advantage for their processing into high-grade poly-urethanes such as, for example, elastomers.